All of these examplesCANNOT move through empty space.
Compressional
The highest point of a transverse wave is the crest and the lowest point is called a trough.
Compressional
CompressionalThe place on the wave that is pushed together is called the compression and the place that is moving apart is the rarefaction.
The wave bends because as it enters a new medium it either speeds up or slows down!
The wave bends because as it enters a new medium it either speeds up or slows down!
The wave bends because as it enters a new medium it either speeds up or slows down!
Refraction and diffraction both cause bending, but refraction occurs when waves move through something, while diffraction occurs when waves pass around something.
26.
Periodic Wave Characteristics
Wave velocity (v)
Distance travelled by a wave
crest in one period
v= λ/T
27.
Wave Behavior
What happens when…
• A wave meets a hard surface like a wall?
• A wave enters a new medium?
• A wave moves around an obstacle?
• A wave meets another wave?
28.
Reflection
• When a wave hits
a surface through
which it cannot
pass, it bounces
back.
• All types of waves
can be reflected.
29.
Reflection
• When a wave hits
a surface through
which it cannot
pass, it bounces
back.
• All types of waves
can be reflected.
30.
Reflection
Reflection does not
change the speed or
frequency of the
wave, BUT the wave
can be flipped
upside down!
31.
Refraction
• The bending of a wave as
it enters a new medium.
• It is caused by a change in
the speed of the wave as
it moves from one
medium to another
– Greater change in
speed = more bending
of the wave
34.
Diffraction
The bending of a
wave as it moves
around an
obstacle or
passes through a
narrow opening.
35.
Diffraction
• The scattering of a
wave as it hits the
edges of a boundary or
tiny opening.
• The wave will try to
curve around the
boundary or outward
through the opening.
36.
Refraction vs. Diffraction
• Both cause
bending, but
refraction occurs
when waves move
through
something, while
diffraction occurs
when waves pass
around something.
37.
Interference
When two or more
waves are moving
through a medium
at the same
time, they may
overlap or combine
together.
39.
Constructive Interference
When two waves combine to make a wave with larger
displacement or amplitude.
–“Helping each other”
40.
Destructive Interference
• Two or more waves combine to produce a wave with
a smaller displacement.
41.
Problem Solving Time!
1. A wave in a spring has a
wavelength of 0.1 meters and a
period of 0.2 seconds. What is the
speed of the wave?
• v= λ/T
• v = 0.1 m / 0.2 s
• v = 0.5 m/s
42.
Problem Solving Time!
2. Find the wavelength of a wave in a
rope that has a frequency of 2.0 Hz
and a speed of 0.4 meters/second.
• v= λ/T; T = 1/f
• λ = v / f
• λ = 0.4 m/s / 2.0 Hz
• λ = 0.2 m
43.
0 cm
5
-10
-5
10
3. What is the amplitude of
the wave?
Amplitude = 5cm
44.
Problem Solving Time!
4. A hiker shouts on top of a mountain
toward a vertical cliff, 688m away. The
echo is heard 4s after.
a. What is the speed of sound?
b. The wavelength of the sound is 0.75m.
What is its frequency?
c. What is the period of the wave?
45.
Problem Solving Time!
a)Speed
v = d/t
v = 688m/2s
v = 344m/s2 s
2 s
4 seconds
46.
Problem Solving Time!
b) Frequency
v = λ/T; f = v/λ
f = 344m/s / 0.75m
f = 458.67 Hz
4 seconds
47.
Problem Solving Time!
c) Period
T = 1/f
T = 1/458.67 Hz
T = 2.18x10-3s
4 seconds
48.
Problem Solving Time!
5. If the frequency of a sound wave is
doubled, what happens to the
period of the same sound wave?
The period will be halved.
49.
Problem Solving Time!
6. If the speed of wave is doubled,
what happens to the frequency of
the same wave if the wavelength is
constant?
The frequency will be doubled.
50.
Problem Solving Time!
6. If the speed of wave is
doubled, what happens to the
frequency of the same wave if the
wavelength is constant?
The frequency will be doubled.
51.
Problem Solving Time!
7. If the wavelength is halved and the
frequency is quadrupled, what will
be the speed of the wave? (in
multiples of v)
2V.
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